Why don’t Japanese cities have walls?

I’d always assumed it was some kind of policy of the shogunate to stop individual cities becoming centres of power and more able to rebel, but the history of Asia I’m reading at the moment says Heian and Nara were notable at the time of their foundation for copying Chinese cities in everything but the walls – walls that Chinese cities very much pride themselves and that the Koreans happily copied. No reason given, unfortunately!

I suppose one aspect is that though there was plenty of internal fighting in Japan there was rarely the danger of outside invasion as there was in China and Korea, but that hardly seems reason enough on its own…

T2 said,

One reason is because the “city / town” built around the castles basically functioned as the “wall”.
That’s why the cities had such narrow streets.

And in feudal Japan, whenever a war broke out, the main aim was to get rid of the opposing clan or warlord. But they wanted to keep the common people since they were needed to work on the crops and whatnot, so even if a war broke out, common people usually didn’t get involved so it wasn’t that necessary to protect the whole city using a wall.
(Of course, that doesn’t mean there were no pillagers,
so people living around the castle were allowed to take shelter inside the castle premises, and commoners who lived a little far away from the castle would provide food to the enemy to be “let off the hook”.)

One other reason for that maybe because Japan is an island.
The war was always “Japanese versus Japanese”,
so speaking in broad terms, unnecessary massacres because of religious differences / racial differences etc. didn’t really happen.
Whereas in China or Europe, there was always a possibility for some other country to try and invade them.

Jish said,

Well, theoretically, as long as there are at least 2 nations, there’s still a threat of war. It was just lessened for the Japanese and was made significantly more difficult (see: the failed Mongol invasions). This also worked the other way around (see: the failed Japanese invasion of China through Korea and Admiral Yi Sun-sin)